Major Forms of Cancer - Skin cancer

With as many as 500,000 new cases occurring annually, skin cancer is the largest single source of malignancy in the United States. An estimated 6,000 persons die of this disease each year. Since 1980, the number of cases of malignant melanoma, the most deadly form of skin cancer, has risen by more than 90 percent.

Experts believe that many cases of skin cancer could be prevented if more people avoided exposure to the sun. Radiation in sunlight not only burns and dries the skin; it also is thought to suppress the human immune system and thus contribute indirectly to skin problems. Long and continued exposure to the sun has been associated with cataracts as well as with skin aging and wrinkling.

Symptoms

Persons with skin problems should report promptly to their physicians any sores that refuse to heal, or changes in warts or moles. Pimples that itch and recur may also be symptoms of skin cancer.

Therapy

Most skin cancers remain localized. They can usually be removed by excisional surgery, with an electric needle, or by cryosurgery (freezing). X-ray irradiation and chemotherapy may also be used.

Causes

Most skin cancers appear after the age of 40. Scientists point to the ultraviolet radiation in sunlight as the primary cause, with ultraviolet-B (UV-B), the shorter wavelength band, as the more dangerous. But dermatologists recommend that ultraviolet-A (UV-A), used often in high-intensity sunlamps and tanning beds, be avoided as well. While UV-A is spread more evenly throughout the day, UV-B is largely concentrated around midday.

Fair-skinned individuals who burn readily, rather than tanning, are more vulnerable to radiation-caused cancer than darker-skinned persons. Geographic location is also important. Skin cancer occurs more frequently in the southern belt of states, particularly in the sunny Southwest.

Chemicals, too, can cause skin cancer. Before the relationship was discovered, skin cancer was an occupational hazard for many thousands of unprotected workers who dealt with arsenic and various derivatives of coal and petroleum.

Kinds

Of the three primary kinds of skin cancer, two are both common and relatively curable. These are basal-cell and squamous-cell carcinoma . Early detection almost ensures that a cure can be effected.

A melanoma , or so-called black cancer , is a malignant tumor that arises from a mole. The moles may begin as flat, soft, brown, and hairless protrusions, but they can change suddenly into darker, larger growths that itch and bleed. They can also metastasize, spreading cancer cells to other parts of the body through the bloodstream and the lymphatic system.

Unlike other types of skin cancer, melanomas may grow in skin areas not usually exposed to the sun, such as the feet, in the genital area, or under the belt or collar. Chronic irritation from tight clothing is one suspected cause. Melanomas rarely occur before middle age; nearly three-fourths of the victims are women.